The legacy of the Olympic Stadium is uncertain, with the Olympic Park Legacy Company keen to secure a role for athletics at the venue. Photograph: Sean Dempsey/PA

The sports minister, Hugh Robertson, has said the government is unlikely to underwrite a bid for the world athletics championships in 2015, once seen as a likely showcase for the legacy use of the Olympic Stadium after the 2012 Games.

UK Athletics and the London Olympic Games Organising Committee chairman, Lord Coe, are keen for the 2015 world championships to come to London but the bid is likely to be withdrawn if they cannot secure government support.

Robertson said an independent study had shown that UK Athletics would not be able to cover the cost of the event from sponsorship and ticket sales, so the government would not be able to commit to underwriting any funding gap.

"The question is not the guarantees around visas and so on. I have said we will do that. The question is how you fill a £25m black hole that lies at the centre of this bid," Robertson said, speaking at an event to showcase the legacy vision for the Queen Elizabeth Olympic Park, as it will be called after the Games.

"Some of this you can fill through sponsorship and other things but it's still going to leave a pretty sizeable commitment. Once you have done it for one sport, then every single other sport trying to mount a bid is going to be after me for the same sort of money."

It is unlikely the government would have to bear the full burden of the losses, which could run to £25m, but Robertson said he was not prepared to take the risk. He said other sports bidding for major events, such as the Rugby Football Union's to host the 2015 World Cup, had needed to prove they were likely to break even before the government would commit to underwrite the cost of hosting them.

Beijing is the only other likely bidder for the 2015 event and the IAAF is expected to look favourably on a European bid. It would be one of the few events capable of filling the Olympic Stadium for athletics if it retains the running track and a capacity of 55,000, as envisaged under the joint bid from West Ham United and Newham council.

Margaret Ford, the Olympic Park Legacy Company chair, stopped short of ruling out the rival bid from Tottenham Hotspur and AEG on the grounds that it proposes to remove the track. But while refusing to comment on individual bids, she signalled it would not be looked on favourably if there was no legacy for athletics. "One of our criteria was they had to tell how us how they would meet the Olympic promise for athletics in legacy. That has not changed," she said.

Robertson added: "It [athletics] was an absolutely core part of our bid ... and that commitment will be honoured." Robertson said there will be no final decision on the world championships until after the comprehensive spending review on 20 October, and UK Athletics will continue to press its case.

"If UK Athletics wants an answer from me on this before then it will be 'no'. I will not make any decision before I know how much money we have to spend. But if I have to make a choice between underwriting losses and funding elite athletes I will choose athletes every time," he said.